El equipo investiga el tiroteo sistemático de una familia que estaba de picnic junto a un río. El caso hace revivir recuerdos de la muerte de una joven junto a ese mismo río hace 10 años.

A medida que el DCI Butcher se acerca a realizar un arresto, el equipo continúa persiguiendo sus propias líneas de investigación. El pasado de Amy comienza a alcanzarla y converger con la investigación del equipo.

The team assists DI Paul Renick following the assumed suicide of Jamal Al Sham and discover that he was murdered and was a people smuggler, blamed by Varkey Khoury, head of a family of Syrian refugees, for killing his wife. Varkey's 15 year old daughter Akka approaches Nikki for news of her mother, leading to Nikki sheltering her whilst the police haul in another young woman Tamara as a likely killer. At the refuge camp in Calais apparent altruist Yusuf Hamed assists 12 year old Sosa to come to England whilst Kalil Aziz, an associate of Sham, is also murdered and the police and pathologists make a grim discovery in an English forest.

Ali is arrested for stabbing Aaron, who discharges himself from intensive care aided by brother Ben and his wife Sarah. Visiting Ali in custody DI Ashton suggests that Chris killed Ruth and gets an angry response whilst illegal immigrant Stella Duffour is interviewed as the person who reported Lorna's death, resulting in her being threatened. The pathologists pick up on the evidence that sent Kieran to embark upon his fatal mission and locate the spot where Ruth was killed. An unusual discovery by Clarissa is also instrumental in catching the murderer and closing the case.

El esposo de Clarissa, Max, es llevado al Centro Lyell para ayudar a resolver un caso.

Durante la búsqueda del equipo por el asesino, Jack trabaja junto a un viejo amigo de Irlanda del Norte y descubren un conflicto complejo.